The invention concerns a tension relieving device for cables or cable sections and particularly seismic cables (streamers) which are towed behind a vessel, where a stretch element is passed in a loop between two end pieces which are designed to be attached to end contact pieces on the seismic cable.
When cables, e.g. seismic cables, i.e. so-called streamers, are towed in the water behind a seismic vessel, the cables are exposed to tension stresses, which not only exert a strain on the streamer in the longitudinal direction, but which can also cause oblique loading in relation to the streamer's longitudinal direction. Such stresses also occur when the streamer is reeled in on the cable reel on board the seismic vessel. If measures are not taken to compensate for such tension stresses a break can easily occur in the cable and the cable's contacts can become deformed, giving rise to points of leakage in the cable. The load-carrying structures with their wires can even be broken or worn away.
In order to counteract such faults and unfortunate effects, tension relieving devices are normally inserted in the seismic cable. A device of this kind is described in U.S. Pat. No. 4,641,288 where between two end elements is attached a band which due to its flexibility should be able to absorb loads, even in other directions than in the cable's longitudinal direction. The tension relieving device in accordance with the U.S. patent will, however, not work in all planes, due in part to the termination in the ends where metal pins are used. There will be no compensation for an oblique load in the same direction as the axis of the pins. Moreover, with the device in accordance with the said U.S. patent problems will be encountered with lead-through of the various wiring components required by the streamer cable.